Synchroscope



Patented Juney 1.8, 1940 smcnnoscora Joseph W. Allen, East Orange, J.,assignorto Eclipse Aviation Corporation, East Orange,

N. J., a corporation of New Jersey Application January 14, 1935, SerialNo. v1,81'!

3 Claims.

This invention relates to indicating apparatus and particularly to meansfor indicating the relationship between the rates of movement of any twoor 'more continuously moving mechanisms such as internal combustionengines installed on an airplane or other craft and subjecty tovariations in speed. Y

An object of the invention is to provide an indicating system includinga synchroscope and means for causing said synchroscope to assume a ofstudy, such as the internal combusion engines above suggested, areoperating in synchronism,

and to display a different type of indication when 1 5 said engines arerotating at different speeds.

This and other objects and advantages willap- -pear more fully from aconsideration of the-detailed description whichfollows, with referenceto the accompanying drawing, wherein is illustrated one embodiment ofthe invention. It is to be expressly understood, however, that thedrawing is for the purpose of illustration only, and is not designed' asa denition of the limits of`the`invention, reference being had for thispurpose t0 25 the appended claims. a.

In the drawing:

Fig. 1 is a combined mechanical and schematic representation of theinvention as applied to two independently rotating bodies S and S';

' Fig. 2 is a graph showing voltage changes during operation.

Reference characters S and S indicate rotating shafts such as thecrank-shafts of two distinct internal combustion engines, or shaftsgeared thereto. On the shaft S there is keyed a ring G of currentconducting material which will be termed a collector ring since itsfunction is similar to that of the conventional collector ring employedin alternating current machines and the reference character G' indicatesa corresponding collector `ring similarly secured .to the shaft S. Asshown, the rings have brushes H and H' associated therewith 'andelectrically connected through the instrumentality of conductors and I2and a voltmeter I3 which in the form of the invention illustratedconstitutes the means on which the speed Arelationship between the twoshafts S and S' is indicated. This meter 3 may be of the ordinarypolarized galvanometer type, as in British Patent No. 191,849 of 1923.

Also engaging the collector ringsG and G respectively, arev a pair ofcurrent 'conducting bars F and F adapted to rotate with commutator barsA andA respectively, to which theyv are 55 secured, the'said bars A andAv being' part com'- definite position or condition when the subjectsmutator assemblies having a plurality of similar current conductingsegments spaced apart but electrically connected through the loopedwind-` ings B and B respectively. At diametricallyop'- posed stationarylocations brush holders C are provided and each contains a brush 30, 3|adapted to be engaged by each of the commutator segments in successionas .the latter rotate with the shaft S, collector ring G, and connectingbar F, the commutator assembly being mechanically connected with theshaft S in any suitable manner not shown. Corresponding iixed brushholders C retain brushes 30', 3|

'segments A' of the comrnutator assembly which rotates with the shaftS', and the brushes are electrically connected in 'parallel relation by`means of conductors 2|, y22, 23, and 24, all leading from a battery Dor other source of direct current.

From the foregoing description it willbe apparent that the conductor Bforms a path for the flow of current from the battery D throughconductor 2| to the' positive brush 30 and thence through the loopedwinding B to the negative brush 3| andv back to the source by way of-conductor 23 while a similar flow of current will take place by way ofconductor 22, positive brush 30', winding B', negative brush 3|', thenconductor 24. Moreover, as the commutators are rotated each collectorring and its associated stationary brush will be successively positiveand negative and since the said brushes are interconnected through theindicator I3 it will be apparent that the indicator, which as abovesuggested is in reality a voltmeter, will give a zero indication so longas the speed of rotation of the two ccomf mutator assemblies A and Aremain identical, for under 'such conditions the brushes H and H' remainat equal values of potentials and there. fore no current flows throughAvoltmeter I3. In .further explanatiom of this action it will be notedthatv in the relative' positions shown in the drawing both collectorrings G and G' areatpositive potential and also at equal values ofpotential. It both commutators are rotated at same rate, the collectorrings will always be at the'sarne potential, hence no. deflection ofthev indicator. If from the positions as shown, the right handcommutator is turned '180, 'the collector ring of the right vhand willbe negative potential. Since now the one side of the indicator isconnected to the left side and positive while the other side ofindicator is connected toA the negative, a maximum deflection to oneside occurs.

which cooperate in a similar manner with the 1f both commutators are nowrotated 180 each, the collector ring on the lei't side would be atnegative potential 4while the collector' ring at right would be atpositive potential. This would provide amaximuiriidefiection to theopposite side of the indicator;

If both commutators are turning at engine speed of say 1800 R. P.'M. andboth connectors F and F are as shown (that is, in phase), there' isalways a zero potential difference between the 2 collector rings. If barF is 180 out of phase with respect to bar F', the potential impressed onthe indicator is a maximum twice each revo.- lution (that is, when leftring is at top and right ring at bottom; also when left ring is atbottom 'and right ring is at top).

The potentials on the indicator would also be zero twice per revolution.Fig. 2 explains this cyclic action graph-` 3l. Due to this action thedirection and magnitude of E. M. F. through conductors F, H, I I,

I2, Hf and F ,change periodically, except when synchronism prevails.Duringsynchronism the bridge ratio remains constant-hence no E. M. F. inconductors I I, I2 and no action in indicator Il.

An incandescent lamp may be used as an indicator. It it stays ldark (orat a uniform brilliancy), the 2 units are in synchronism. When the lightis dark and bright alternately, the

number of such alternations is a measure of the difference inrevolutions of the 2 units.

A thermo-electric, or well damped, indicating instrument for D. C. andA. C. could be used instead of a lamp and the amount of deiiection couldbe used as a measure or indication oi' actual phase diiierence of theuni Likewise other changes ymay be made in the type oi" indicatoremployed as well as in the arrangement of the electrical connections andthe system.

parts entering into the system of appended claims.

'What is claimed is:

l. In an indicating system,` the combination of a pair of continuouslyrotating commutators, each having a plurality of current conductingsegments, a coiled conductor rotatable with each commutator and tappedintoeach of said segments, means including fixed brushes engageable withsaid segments to send equally divided parallel currents throughequilinear sections of both said coiled conductors, a collector ringelectrically connected with a predetermined segment on each of saidcommutators, additional iixed brushes engaging said collector rings,means constantly in circuit with said last named brushes to indicatewhether said commutators are rotating in or out of synchronism, and asingleexternal` source of current in circuit with both said commutators,and constituting the only current supply means for the system` l 2. Inan indicating system, the-,combination of a pair of continuouslyrotating commutators. each having a plurality of current conductingsegments, a coiled conductor rotatable with each commutator and tappedinto each of said segments, means including fixed brushes engageablewith said segments to sendv equally divided parallel currents throughequilinear sections of both said coiled conductors, a collector ringelectrically connected with a predetermined segment on each of saidcommutators, means constantly in circuit with said collector rings toindicate whether said commutators are rotating .an or out ofsynchronism, and a single external source of current in circuit withboth said commutators, and constituting the only current supply meansfor within the scope 3. Means for indicating whether two continuouslyrotating bodies are or are not in synchronism, said means comprisingcoiled conductors rotatable with said bodies, a source of current, acircuit from said source to said coiled conductors, said circuitincluding means dividing said coiled conductors into parallel paths forreception of current from. said current source, and means electricallyconnected with said dividing means to respond to theresistancerelationship between said parallel paths.

JOSEPH W. ALLEN.

